It is known in chromatography, in particular gas chromatography, to use collectors for the microextraction and subsequent analysis of substances to be analysed, for example in the form of exchangeable tubular sample vessels, known as liners, through which carrier gas can flow; these liners are provided with a layer or filling of a sorbent and/or adsorbent material for receiving the substances to be analysed. These may be collectors which take up and enrich the substances to be analysed externally from liquids and/or gases, in order for them then to be introduced into a chromatographic system, where the substances are desorbed (if appropriate by thermal means) and analyzed. However, the collectors may also be adsorption traps or cryotraps in the chromatographic system. Medium flows around or through the collectors for the purposes of desorption.
It is known to design collectors in the form of small tubes which have an internal coating of the sorbent and/or adsorbent material. However, this internal coating has a relatively low uptake capacity.
The latter is improved by providing a granular filling of the sorbent and/or adsorbent material. A filling of this type, if it allows absorption, as is the case with polyorganosiloxanes, offers a sufficiently large mass, or even a mass which is too large in relation to what is required. However, it is difficult to produce the filling material with a uniform particle size. In the collectors, this leads to different flow resistances for the passage of fluids, which are required at least during the desorption, and may even lead to blockages. The relatively high mass generally has an adverse effect on the chromatogram, on account of a strong background produced by corresponding “bleeding”.